Siemens medium voltage vacuum switch technology and components

Siemens medium voltage vacuum switch technology and components

Basic Information

Siemens medium voltage vacuum switch technology and components are mainly aimed at the medium voltage power system and industrial application fields, providing a comprehensive introduction to vacuum switch technology and related components. The document mentions that all Siemens related products have passed ISO 9001 (Quality Management), ISO 14001 (Environmental Management), OHSAS 18001 (Occupational Health and Safety) system certification, and comply with international standards such as IEC (International Electrotechnical Commission) and IEEE (Institute of Electrical and Electronics Engineers). Some products are compatible with Chinese GB/DL standards.

Medium Voltage Core Concepts and Application Scenarios

1. Definition of voltage level

Medium voltage: AC voltage ranging from 1kV to 52kV, mainly used for power distribution and industrial networks;

Low voltage: AC voltage ≤ 1kV or DC voltage ≤ 1.5kV;

High voltage: used for power transmission (specific scope not specified in the document, focus on medium voltage).

2. Typical application scenarios

Common voltage levels for specific scenarios in the field

Power system power station (generator circuit, ≤ 24kV), primary distribution station (high voltage to medium voltage), secondary distribution station (medium voltage to low voltage) 10kV-40kV (distribution network)

Industrial plants (powered by motors), mining, ships, 3kV-15kV (motor operating voltage)

Special fields (traction power supply) Germany/Austria/Switzerland (AC 15kV, 16.7Hz), other regions (AC 25kV, 50Hz), DC railways (≤ 3kV) AC 15kV/16.7Hz, AC 25kV/50Hz

3. Operating stress of medium voltage equipment

Medium voltage equipment needs to withstand various operating stresses, which is the core basis for selection and design:

Dielectric loss strength: able to withstand normal operating voltage (including fluctuations) and overvoltage (operation/lightning overvoltage);

Current carrying capacity: continuously carrying normal current, short-term carrying overcurrent, and instantaneous carrying short-circuit current;

Current on-off: on-off normal current, fault current, and special current (capacitive/inductive current, high-frequency transient current);

Isolation requirements: In the disconnected state, the safety isolation distance specified by the standard must be met for easy maintenance;

Operation frequency: It is necessary to adapt to multiple on-off operations in a short period of time (such as multi segment reclosing of the recloser).

Core technology: Vacuum arc extinguishing technology

Vacuum arc extinguishing technology is the core of Siemens medium voltage switchgear, which has the advantages of high reliability, long life, and low maintenance. The specific characteristics are as follows:

1. Arc extinguishing principle

When the contacts separate in the vacuum arc extinguishing chamber, a metal vapor arc is generated, and current flows through the metal vapor plasma; The arc automatically extinguishes when the current crosses zero, and the remaining metal vapor loses conductivity within a few microseconds. The insulation ability of the contact gap quickly recovers (with a recovery speed of 5kV/μ s), and can immediately withstand external voltage.

2. Key technological advantages

Low current cutoff: Using special contact materials, the cutoff current is only 2A-3A, avoiding excessive overvoltage when small currents are turned on and off;

Low arc voltage: The arc voltage is only 20V-200V, with low arc energy, minimal contact wear, and long equipment life;

Maintenance free: The vacuum environment is free of oxidation and impurities, and the arc extinguishing system does not require regular maintenance.

3. Contact type and applicable scenarios

Contact type, structural characteristics, current adaptability range, advantages, application product examples

Radial magnetic field contact cup-shaped/spiral structure, generating radial magnetic field ≤ 10kA (diffusion arc); >10kA (contraction arc, arc rotation) universal circuit breaker (3AH5) to avoid local overheating and uniform wear of contacts

Axial magnetic field contact disc-shaped structure, generating high axial magnetic field current (arc always spreads), uniform force on the contact surface, no local melting, high-capacity circuit breaker (3AH3)

Classification and Technical Parameters of Medium Voltage Equipment

Medium voltage equipment is divided into switch devices (for current switching) and non switch components (for protection, measurement, and auxiliary functions). The specific classification and key parameters are as follows:

1. Switchgear

(1) Vacuum circuit breaker

Vacuum circuit breakers can switch between normal and short-circuit currents, suitable for indoor and outdoor scenarios. The core models and parameters are as follows:

Type, Model, Series, Applicable Scenarios, Key Parameters (Maximum), Operating Mechanism

Indoor Circuit Breaker SION 3AE General Scenario (Industrial/Distribution) Rated Voltage 24kV, Rated Current 2000A, Short Circuit Breaking Current 40kA Spring Energy Storage Mechanism

3AH5 economical type, rated voltage for small capacity scenarios is 17.5kV, rated current is 2000A, short-circuit breaking current is 31.5kA, spring energy storage mechanism